Miller’s co-promoter Dmitry Salita confirmed the news, saying: ‘We are in the process of obtaining further information about VADA’s finding and will have more to say soon on this developing situation.

‘In the meantime Jarrell continues to train for his June 1 fight against Anthony Joshua.’

According to ESPN’s Dan Rafael, Miller has tested positive for banned substance GW1516, also known as Cardarine.

The main benefit of the drug is to increase power and endurance for the obese and the elderly, allowing athletes to train longer and harder, and was added to the banned substances list shortly after the 2008 Olympics.

AJ is likely to stick with the June 1 date if Miller is suspended but will need a new opponent (Getty)

The prospect of the fight being called off would be a huge blow for Joshua, who had struggled to find an opponent after failing to agree terms with both Deontay Wilder and Tyson Fury.

Miller – who ironically accused Joshua of using steroids throughout a heated press tour to promote the fight – would likely be handed a one-year suspension.